[NJARC] hallicrafters S-39 help

[Jim Whartenby]

The S-39 is alive and receives something on all bands.  A quick check shows that the battery tube filaments are not balanced with one string at 7.5 volts and the other at 5 volts.  Will have to look into the imbalance, probably the power resistor is out of spec.
It took a bit longer to replace the electrolytic capacitors then I had expected.  The previous rebuild effort had gutted the plug in cans and used new (for 1975) caps.  New and much smaller electrolytic capacitors were soldered and hot glued in place.  
There was one bad tube but the rest checked out OK.  At first turn on, and after a wait for the 35Z5s to warm up, I measured no B+ on the plate of the last audio so a bit of panic set in.  Turned out that switch for Standby ON means B+ is applied and Standby OFF means no B+.  Not what I expected!
Once I correct the filament imbalance, alignment is next.  Jim

      From: Jim Whartenby <antqradio at sbcglobal.net>
 To: "njarc at mailman.qth.net" <njarc at mailman.qth.net> 
 Sent: Tuesday, July 3, 2018 10:26 PM
 Subject: Re: [NJARC] hallicrafters S-39 help
   
In case anyone finds themselves working on an S-39 in the future, let me share my experience, so far.
The Rider book pages starting at 16-20 for the hallicrafters S-39 is in error.  Schematic seems to be OK but the parts values, at least for resistors in the BFO, is not correct.  The listing found on BAMA is the S-39 owner's manual and does agree with what I have seen so far.  
At this point, the first and second audio stages are now debugged and so is the BFO and noise limiter.  Several wiring errors have been cleared in these stages.  I suspect that things will move a bit faster now since the chassis becomes less crowded as I move toward the front end.
One interesting mod that I have left intact is the replacement of the BFO gimmic coupling capacitor with a 1 mmFd mica capacitor.  The gimmic is a three turn coupling cap, per the schematic, which is probably less then 1 mmFd but at this time I don't feel the need to replace it.
One other question, what do the technicians use for insulation sleeving (spaghetti) in the club sponsored repair clinics?  I have been adding sleeving as I pull parts to check their values.  
Have a happy and safe 4th of July,Jim

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